More recently, there has been an increasing interest in distributed learning problems arising from its extensive use in areas like machine learning [1]}, sensor network [2]}, smart grids [3]}, and so on. A distinctive feature of this class of problems is that all nodes collaboratively solve a learning problem without knowledge of the global gradient information. In the setting, nodes transmit local estimates to each other with its immediate neighbors, which in turn makes nodes converge asymptotically to the optimal point.
